Single frequency network (SFNs) are often employed to broadcast information to users throughout a cellular or like network. When employing SFN techniques in a cellular network, adjacent base stations will transmit the same information at the same time using the same radio resources. By having multiple base stations transmit the same information at the same time using the same resources, the signals transmitted from the different base stations effectively reinforce each other and therefore increase the spectral efficiency of the overall network with respect to the signals being transmitted. Increases in spectral efficiency are greatest along cell boundaries where multiple relatively weak signals combine with each other to increase the effective power associated with the transmitted signals. As such, the transmitted signals are readily received along the cell boundaries because the effective power of the transmitted signals is increased and the potential for interference is decreased.
However, the benefits of SFNs are not without compromises. Throughout an SFN, different channel qualities may occur due to base station locations, cell sizes, interference levels, physical topologies, neighboring transmissions, and the like. If each base station in the SFN of a cellular network has to transmit the same information at the same time using the same resources, the entire SFN must be designed to accommodate those cells or areas having the worst channel quality. Since the areas with the worst channel quality dictate the resources for the entire SFN, those areas with relatively high channel quality are theoretically using more resources than are necessary for broadcasting the data of the SFN. These resources could be better used for supporting traditional voice, data, or other media applications. As such, the efficiency of SFNs is significantly constrained, especially in SFNs where there is significant variation in channel quality from one area of the cellular network to another.
Accordingly, there is a need to improve the efficiency of SFN networks, while retaining the improved spectral efficiency that is normally associated with SFNs.